The McGowan Government's legal dispute with construction company John Holland over the delayed completion of the Perth Children's Hospital is becoming increasingly acrimonious, with Treasurer Ben Wyatt accusing the firm of treating him like a fool.

Key points:

The Perth Children's Hospital opened three years late after a string of problems

The WA Government and John Holland are suing each other over the delayed project

The two sides were negotiating, but now it seems the dispute will land in court

He refused to confirm reports the Government had offered $20 million dollars to John Holland to resolve the issue, describing it as a "well used" litigation tactic by the firm, as head contractor of the project, to try and force the Government to compromise its position.

Mr Wyatt said he would prefer to negotiate an agreement but that was now unlikely and the dispute would probably head to court.

Both sides launch damages claims

Both parties are seeking damages from each other over the $1.2 billion hospital, which opened three years behind schedule in May last year after a string of construction problems, including lead found in the drinking water.

The Government wants compensation from John Holland for the delays in reaching practical completion of the hospital.

John Holland is seeking more than $300 million in damages from the Government for what it has previously stated were "significant changes that the state made to our scope of works on PCH".

Mr Wyatt said he was angry at John Holland's tactic of negotiating what could be protracted litigation through the media.

The Treasurer did not deny the Government had made an offer to the company to settle the dispute but said he would "of course not" be happy if taxpayers had to give John Holland any money at all.

"It would be a travesty for me to comment in the media in response to what is a clear litigation tactic by John Holland, for selective media leaks to get me to come out and say something that might compromise the position. I'm not going to do that," Mr Wyatt said.

"I don't want to go to court, but suffice to say I'm also simply not going to be treated like a fool by an organisation that wants me to write a big cheque.

"It's not going to happen that way. So I was hoping this would be resolved, but it appears with this latest leak from John Holland that's likely to be where we go."

Builder says it is owed compensation

In a statement from November 2017, the company said it had "at all times and in good faith, cooperated with all of the state's requests, which were the cause of significant delays to PCH".

"The state has consistently given assurances that it would compensate John Holland for the changes to scope that it requested."

The company said it was committed to achieving a fair outcome for both parties.

Opposition Leader Mike Nahan said the Government had clearly made some sort of offer to John Holland.

"This is an issue of accountability. The Government took possession when it shouldn't [have] and with great bravado said it was going to get money from John Holland. It's blown up in its face," Dr Nahan said.